Ephemeris: 06/24/2024 – Waiting for a bright nova*

This is Ephemeris for Monday, June 24th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 3 days past full, will rise at 12:09 tomorrow morning.

The small constellation of Corona Borealis, or Northern Crown appears about a third of the way between the bright star Arcturus, high in the south and the star Vega in the east. It is a small semicircle of stars with the brighter star called Alphecca near the center of the arc of stars. Sometime this year, we hope, another bright star will appear there. A nova of a dim star brightening about 1,600 times normal near that circle of stars. It has done it before. It has the designation of T Coronae Borealis (T CrB for short), and is a recurrent nova of a white dwarf star that suffers an explosion about once every 80 years. So this year we need to be looking out for that stellar explosion, which will be bright for only a few days, so one must be vigilant to spot it.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

* The word ‘nova’ comes from the Latin Nova Stella, meaning New Star.

Addendum

Putting Corona Borealis in context with the Big Dipper, to the upper right, looking overhead while facing south, at 11 pm in late June. Created using Stellarium and GIMP.

This animated GIF shows the constellations of Hercules, Corona Borealis and Boötes from left to right. Flashing on and off is T Coronae Borealis (T CrB). It is shown at its approximate maximum brightness, about the same as Alphecca (spelled Alphekka here). Created using Stellarium and GIMP.

Light curve for Nova Cygni 1975 (V1500 Cyg) which burst forth in the constellation of Cygnus the Swan in August of 1975, just two months after the beginning of the Ephemeris program. There hasn’t been a brighter one since. Notice the initial sharp rise and initial decline. Magnitudes (Mag on the vertical axis) work like golf scores or prizes, the brighter the star the lower the magnitude number. The dimmest star visible to the naked eye is about 6th magnitude. You can blame Hipparchus for that numbering scheme.

NASA has post about T CrB here: https://www.nasa.gov/centers-and-facilities/marshall/nasa-global-astronomers-await-rare-nova-explosion/

Ephemeris: 06/21/2024 – Saturn’s rings are almost edge-on this year

This is Ephemeris for Friday, June 21st. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, at full today, will rise at 9:57 this evening.

Saturn’s rings change their aspect or their tilt to us over a period of nearly 30 years, the time it takes Saturn to orbit the Sun. Saturn has an axial tilt like the Earth does in its case it is 27° compared to the Earth’s 23 1/2 degrees. So as Saturn moves around the Sun and us we see those rings at different tilts to us. Currently, the angle of the rings to us is nearing zero degrees, meaning that they are going edge on to us. And being perhaps less than 100 meters thick, they will disappear entirely in telescopes from the Earth. That will happen on March 23rd next year. However, they will not go edge on to the Sun until May 6th. So between March 23rd and May 6th we will be we will be looking at the unlit or dark side of the rings. Since we’re not at in line with the Sun and Saturn, the Sun will still be illuminating the rings slightly, but we will be looking at the dark side of the rings.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

How the appearance of the rings change as Saturn orbits the Sun. Credit: NASA Hubble.

Ephemeris: 06/20/2024 – Summer starts this afternoon

This is Ephemeris for Thursday, June 20th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 1 day before full, will set at 4:59 tomorrow morning.

Well, this is it, the summer solstice! Summer will begin at 4:51 this afternoon. In the Southern Hemisphere the season of winter will begin, and the South Pole of the Earth in the middle of its six months of darkness. Maybe we should call it the June solstice, because winter also begins in the Southern Hemisphere. The north above 66 ½ degrees north latitude is the land of the midnight Sun. Over summer that line will creep northward as the Sun heads southward. The seasons are caused by the tilt of the Earth’s axis, not by the Earth’s change in distance from the Sun. In fact, we are approaching our farthest distance from the Sun, of about 94.5 million miles (152 million kilometers) on July 5th, called aphelion. The greater than normal distance makes summer the longest season at 93.7 days, winter being the shortest at 89 days. The Sun will be at its highest, of just under 69 degrees altitude at 1:44 pm for the Interlochen/Traverse City area, and about a degree lower than that in the Straits area, though their daylight hours will be 12 minutes longer.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

Comparing the Sun’s path at the summer and winter solstices in Traverse City, MI, US. This is a stereographic representation of the whole sky which distorts the sky and magnifies the size of the Sun’s path near the horizon. Created using my LookingUp app and GIMP.

Ephemeris: 06/19/2024 – Where have the naked-eye planets wandered off to this week?

This is Ephemeris for Juneteenth, Wednesday, June 19th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 2 days before full, will set at 4:15 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week, and see what planets are left. Venus and Mercury are too close to the direction of the Sun to be seen. Both are on the evening side of the Sun, but lost in its glare. It will appear in the evening sky next month. By 5:15 tomorrow morning, or about 45 minutes before sunrise, Saturn will be in the southeast and Mars will be lower in the east, and Jupiter will be very low in the east-northeast. In telescopes, Saturn will look fairly different this year and next with its rings nearly edge on to us. Saturn will rise at 1:35 am, Mars at 3:19 am, and Jupiter, making its first morning appearance, will rise at 4:38 am.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

The Moon as it might appear in binoculars or a small telescope at 11 PM tonight, June 19th 2024. Selected features are labeled. Created using Stellarium, LibreOffice Draw, and GIMP.

Translations of some lunar feature names according to Virtual Moon Atlas

Lacus Mortis – Lake of Death
Lacus Somniorum – Lake of Dreams
Mare Cognitum – Sea of Knowledge
Mare Crisium – Sea of Crises
Mare Fecunditatis – Sea of Fruitfulness
Mare Frigoris – Sea of Cold
Mare Humorum – Sea of Moisture
Mare Imbrium – Sea of Showers
Mare Nectaris – Sea of Nectar
Mare Nubium – Sea of Clouds
Mare Serenitatis – Sea of Serenity
Mare Tranquillitatis – Sea of Tranquility
Mare Vaporum – Sea of Vapors
Montes Alpes – Alps Mountains
Montes Apenninus – Apennines Mountains
Oceanus Procellarum – Ocean of Storms
Sinus Iridium – Bay of Rainbows
Sinus Medii – Central Bay
Sinus Roris – Bay of Moisture

Craters are named for persons, real or otherwise.

Saturn, Mars and Jupiter as they might be seen low in the east and southeastern sky at 5:15 AM, or about 45 minutes before sunrise, tomorrow morning June 20, 2024. Saturn will rise at 1:31 AM, Mars at 3:14 AM, and Jupiter at 4:31 AM. Click or tap on the image to enlarge it. Created using Stellarium.

Telescopic Saturn and Jupiter (north up) as they would be seen in a small telescope at 5 AM June 20th 2024 with the same magnification. Apparent diameters: Saturn 17.57″, its rings 40.95″; Mars, too small to be represented here, is 5.25″; Jupiter 33.20″. Note the ” means seconds of arc, or 1/3600th of a degree. Created using Cartes du Ciel (Sky Charts).

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on June 19, 2023. The night ends on the left with sunrise on the 20th. Click or tap on the image to enlarge it. Created using my LookingUp app and GIMP.

Ephemeris: 06/18/2024 – Are we in a space race with China?

This is Ephemeris for Tuesday, June 18th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 3 days before full, will set at 3:41 tomorrow morning.

Back in the late 1950s and early 1960s The United States and Russia were in a space race, attempting to outdo each other in space. The Russians had the lead to begin with. Their rockets were bigger because they were unable to miniaturize their atomic weapons. So they needed rockets large enough to launch them, and had rockets large enough, off the shelf so to speak, to be able to launch satellites and even humans into orbit. Sixty years later the old Soviet Union has disappeared and Russia is still using rocket technology that was developed in the 1960s. The Chinese however, were nowhere in the 1960s, and have now ascended to be our number one competitor in space. Considering their latest progress, China may beat us back to the Moon.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

The Chinese Chang’e 6 the sample collection spacecraft with the sample collection arm, taken by a minirover that was ejected out of the spacecraft is it landed in the Apollo crater on the far side of the Moon . © CNSA (China National Space Administration).

Ephemeris: 06/17/2024 – China’s mission to get samples from the far side of the Moon

This is Ephemeris for Monday, June 17th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 3 days past first quarter, will set at 3:16 tomorrow morning.

Earlier this month the People’s Republic of China’s Chang’e 6 spacecraft landed on the far side of the Moon to collect samples to return them to the Earth. They had put a satellite in orbit of the moon to act as a relay satellite so they can communicate with their Lander. The collection went according to plan and the spacecraft is now headed back to the Earth. It is my understanding that they landed in the crater called Apollo at the edge of the Aitken basin . Being the far side of the moon the Apollo crater is not named for the Greek god but for the American human Moon program of the 1960s and early 70s. The samples are expected to return to Earth on the 25th. These are the first samples from the far side of the Moon to be returned.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

The far side of the Moon as shown in the Virtual Moon Atlas with my annotations. The Chang’e 6 sample return mission landed in the Apollo crater near the edge of the Aiken Basin, the largest, deepest and oldest impact structure on the Moon. The Chang’e 4 and Yutu 2, lander and rover, landed elsewhere in the Aitken Basin.

Ephemeris: 06/14/2024 – Star Party at the Sleeping Bear Dunes tomorrow night*

* if it’s clear or mostly clear.

This is Bob Moler with Ephemeris for Flag Day, Friday, June 14th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:30, and it will rise tomorrow at 5:56. The Moon, at first quarter today, will set at 2:22 tomorrow morning.

Tomorrow night, Saturday, June 15th, the Sleeping Bear Dunes National Lakeshore will team up with the Grand Traverse Astronomical Society to host a star party at the Dune Climb from 9 to 11 PM. It won’t be a star party exactly, because the featured attraction will be the Moon, nearly two days after first quarter. To my mind, this is about the best time to view the Moon showing its craters with deep shadows near the terminator or sunrise line which crosses the moon slowly over the month. There are no planets out in the evening, but we do have some interesting stars to look at besides the Moon. The fairly bright Chinese Tiangong Space Station will pass below the position of the Moon at 10:22 that evening.**

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

This is a simulated image from Stellarium of what the Moon might look like tomorrow night. This is the right side up view that one might see in binoculars. However, depending on the telescope one is looking through, the image could be rotated or even be a mirror image. So be aware of that. The craters are named after persons. The other features are English translations of the Latin names. Created using Stellarium, LibreOffice Draw, and GIMP.

** The information of the Tiangong space station pass came from heavens-above.com. The space station was also displayed in Stellarium when set to the proper time. Tiangong was predicted to be first magnitude by both sources, but Heavens-Above predicted a magnitude twice as bright as Stellarium.

Ephemeris: 06/13/2024 – The Apollo 11 flag

This is Ephemeris for Thursday, June 13th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 1 day before first quarter, will set at 2:06 tomorrow morning.

Tomorrow is Flag Day. That got me to thinking about the flags that the Apollo astronauts planted on the Moon and what state they are in. We know the Apollo 11 flag was blown down by the blast of the ascent stage engine when they left the Moon because it was planted too close to the lunar module. The other five flags are still standing. However, there’s some speculation as to what color they are. Are the colors bleached out by the ultraviolet of the sun’s light, which is unimpeded on the Moon? The flags may be bleached completely white. There was nothing really special about the flags that NASA used for the Apollo mission so they weren’t especially prepared to withstand the rigors of being out and undiluted sunlight.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

Buzz Aldrin saluting the flag on Apollo 11. The flag was procured from government sources and made of nylon. It was folded and rolled up with the flagpole and the horizontal bar that holds the flag out. It was placed in a tube attached to the leg of the lunar module. So when unfurled it turned out to be fairly wrinkly and of course there’s no wind on the Moon to cause the flag to flutter, this is just wrinkles. Credit: NASA, Neil A. Armstrong.

The Apollo 11 flag assembly before being packed. Credit: NASA, via Wikipedia.

Ephemeris: 06/12/2024 – Where are the naked-eye planets this week?

This is Ephemeris for Wednesday, June 12th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 2 days before first quarter, will set at 1:49 tomorrow morning.

Let’s find out where the naked-eye planets have wandered off to this week, and see what planets are left. Venus and Mercury are too close to the direction of the Sun to be seen. Venus just entered the evening sky last week when it passed behind the Sun in conjunction. It will appear in the evening sky next month. Jupiter, the second-brightest planet still is a week or so from being spotted in the morning, since it rises about an hour before the Sun. By 5 tomorrow morning, or about an hour before sunrise, Saturn will be in the southeast and Mars will be lower in the east. In telescopes, Saturn will look fairly different this year and next with its rings nearly edge on to us. They will open up a bit through October before closing again. They are only 2 degrees from being edge on to us.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

The moon as it might appear in binoculars or a small telescope at 11:00 PM tonight, June 12th 2024. Selected features are labeled. Created using Stellarium, LibreOffice Draw, and GIMP.

Saturn and Mars as they might be seen low in the east and southeastern sky at 5 AM, or about an hour before sunrise,tomorrow morning June 13, 2024. Saturn will rise at 3:48 AM, Mars at 4:36 AM. Created using Stellarium.

A much enlarged telescopic view of Saturn, much larger than is available in the small telescope . I did this to better show the almost edge on rings. The apparent diameter of Saturn is 17.36″, and the rings extend to 40.44″. The tilt of the rings is only about 2° from being edge on . When the rings are tilted to their maximum extent, this was seven years ago, Saturn was much brighter because the rings can reflect more light from the sun than the planet does. Created using Cartes du Ciel (Sky Charts).

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right tonight, June 12th 2024. The night ends on the left with sunrise tomorrow morning on the 13th. Click or tap on the image to enlarge it. Created using my LookingUp app and GIMP.

Ephemeris: 06/11/2024 – The man who first mapped the Moon

This is Bob Moler with Ephemeris for Tuesday, June 11th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, 3 days before first quarter, will set at 1:31 tomorrow morning.

Ever wonder where the names of the features of the Moon come from? Most of the large features on the Moon were named by Giovanni Battista Riccioli, a Jesuit priest of the 17th century. He created the first accurate map of the Moon in 1651, and he named the features he drew including the Sea of Tranquility (Mare Tranquillitatis), the craters Tycho, Plato, Clavius and many others that I talk about. Even though he professed the Earth centered universe, he gave the heliocentrists Copernicus, Kepler and Aristarchus prominent craters, but in the Ocean of Storms, Oceanus Procellarum, denoting the controversy of the day. Riccioli’s nomenclature became the standard for the Moon and other planets and moons.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

Giovanni Battista Riccioli

Riccioli’s 1651 map of the Moon with many features labeled. Click or tap on the image to enlarge it.

Tonight’s Moon (06/11/24). Can you relate tonight’s Moon to Riccioli’s map? Click or tap on the image to enlarge it. Created using Stellarium.